Substituted anthraquinones

ABSTRACT

ANTHRAQUINONES HAVING AT THE 2 AND THE 6 POSITIONS SUBSTITUENTS SELECTED FROM THE GROUP CONSISTING OF   R-N(-R)-(1,4-PHENYLENE)-CH=N- AND   R-N(-R)-(1,4-PHENYLENE-CH=CH=N-   WHEREIN R IS LOWER ALKYL. THE COMPOUNDS ARE USEFUL AS DICHROIC PHOTOCONDUCTORS AND AS PHOTOSENSITIZERS FOR PHOTOCONDUCTIVE POLYMERS SUCH AS POLYVINYLCARBAZOLE.

United States Patent ABSTRACT OF THE DISCLOSURE Anthraquinones having at the 2 and the 6 positions substituents selected from the group consisting of wherein R is lower alkyl. The compounds are useful as dichroic photoconductors and as photosensitizers for photoconductive polymers such as polyvinylcarbazole.

FIELD OF THE INVENTION The present invention is concerned with the preparation of novel anthraquinones having certain substituents at the 2 and the 6 position and with their use as photoconductors.

PRIOR ART Although numerous other substituted anthroquinones have previously been known, the compounds of the present invention are entirely novel to the best of our knowledge.

SUMMARY OF THE PRESENT INVENTION 2,6-diaminoanthroquinone is condensed with p-di-lower alkylaminobenzaldehyde or p-di-lower alkylaminocinnamaldehyde to yield the novel compounds of the present invention, which have the formula:

with X being selected from the group consisting of wherein R is lower alkyl.

and

The novel compounds of the present invention are photoconductive and also exhibit a very high degree of dichroism. They are useful as components of photoconducting plates in electrophotographic processes, particularly by the contact reflex method, as described in US. patent application Ser. No. 668,697 filed Sept. 18, 1967 by C. 'E. Herrick and M. D. Shattuck.

For the preparation of photoconductive elements, it is advantageous for the compounds of the general formula to be dissolved in organic solvents, such as tetrahydrofuran, or any other solvent in which the compounds are at least partially soluble. Such solutions are applied to substrates suitable for electrophotography and the solvent is then removed. Mixtures of solvents can also be used.

Instead of the above preparation, the compounds of Patented May 4, 1971 the general formula can be used in conjunction with a resinous binder. Suitable resins include both natural and synthetic resins, examples of which are balsam resins, phenol resins modified with colophony, coumarone resins, indene resins, cellulose ethers, polyvinylchlorides, polyvinylacetate, acrylic polymers, such as polymethylacrylic esters, polystyrene, polyisobutylene, polyvinylnormal, polycondensates, such as phthalate resins, polyamides, and polyadducts, such as polyurethanes.

The proportion of resin to the photoconductive compound can vary greatly, but elements having a high proportion of resin and a low proportion of photoconductive compound 'are the less desired. Mixtures of at least equal parts resin and photoconductive compound are preferred.

The substrate material, if one is desired, may be any which satisfy the requirements of electrophotography such as metal, glass, paper, or plastic. Unless it is to be used in a device employing dual corona discharge, such as US. Pat. 2,922,883, the substrate should preferably have a conductivity greater than 10- ohm- CHIC-1.

Application of the solutions of the compounds of the general class, with or without resins, is in the usual manner, such as by spraying, doctor blade, meniscus coating, etc., followed by drying.

One type of electrophotographic process in which the compounds of the present invention are useful is known as xerography. This process comprises the laying down of the uniform electrostatic charge on a photoconductive insulating element, exposing the electrostatic charge surface to a pattern of light to effect a decay of charge in illuminated areas, and contacting the latent electrostatic image thus formed with colored electroscopic powder to render the image visible. Next, a copy sheet is brought into contact with the developed image and transferred thereto and fixed thereon. The residual toner remaining on the photoconductive insulating element is removed by cleaning and the element is then ready for the preparation of the next copy of the next cycle.

Because they have the additional advantage of being dichroic, the compounds of the present invention are suitable for use in that type of electrophotography known as contact reflex reproduction, which is an electrophotographic process for the production of reflex copies in which a document is positioned adjacent a photoconductive element which exhibits photoconductive dichroism and has a preferred absorption axis, and in which the photoconductive element is uniformly exposed through the photoconductive element with polarized light whose vector, relative to the absorption axis, is such that the light is not absorbed. The polarized light in striking the document is absorbed in some areas, normally the dark image areas, and depolarized and reflected in others, normally the light background areas. The light from the reflected areas, being depolarized, contains light with an electric vector which will be absorbed by the photoconductive element and the element is thus exposed to a pattern corresponding to the pattern of the document. This renders the photoconductive element conductive and capable of transporting an electrostatic charge and, hence, permits the formation of an electrostatic charge pattern corresponding to the document.

PREFERRED EMBODIMENTS The general nature of the invention having been set forth, the following examples are now presented as to 'the specific preparation of compounds falling within the 3 EXAMPLE I tial of +7000 volts. After charging, the element was exposed to a 375 Watt GE Photo EBR lamp at a distance bls (p-dlmethylammobenzyhdeneammo)910 of 12 inches for 0.1 second and using positive transparency anthraquinone A mixture of 2 g. of 2,6 diaminoanthraquinone and 15 g. as a document to be copied. The formed electrostatic of p-dimethylaminobenzaldehyde were heated at 240- 15 image was developed with negatively charged toner 250 C. for about 15 minutes. The reaction mixture was (Xerox 914) across the photoconductive element. Again cooled, triturated with acetone and filtered. The dark solids using the Xerox Model D Processor, the toner image was were then slurried in hot dimethylformamide and filtered. transferred to paper by spraying positive charges on the These solids were analyzed and were shown to be the back of the paper. After transfer of the toner image, the title compound by the following results: toner was fused to the paper on a hot plate to yield a Calcd. for C H N O (percent): C, 76.78; H, 5.64; high quality copy of the document with high contrast, N, 11.19. Found (percent): C, 76.65; H, 5.55; N, 11.31. high image density, and faint background.

EXAMPLE II EXAMPLE V 2,6 bis(pdimethylaminocinnamylideneamino)9,10 Aluminized cellulose acetate is coated by means of a anthraquinone meniscus coater with 4% of a copolymer of methyl vinyl A mixture of 1 g. of 9,10-anthraquinone and 3.5 g. of ether and maleic anhydride in water. The film is allowed p-dimethylaminocinnamaldehyde were heated at 240-25 0 to air dry overnight.

C. for 15 minutes. The reaction mixture was then treated The compound of Example I above is applied to the in the same manner as in Example I. The dark solids above film by hand application in a linear direction along were analyzed as follows. the length of the web. On top of this there is coated Calcd. for C H N O (percent): C, 78.24; H, 5.83; the following formulation: N, 10.14. Found (percent): C, 77.99; H, 5.83; N, 10.31. 40 g 10% polyvinyl carbazole in benzene EXAMPLE III 20 g. benzene A photoconductive element was prepared by dispersing tcliloroform 2,6 bis (p dimethylaminobenzylideneamino)9,10 anthra- 0 'g g g phthalene quinone (the compound prepared in Example I above) p in an equal weight of polystyrene dissolved in 1,2-dich lo- 8 g gz gz ggi g g of plflstlclzfel' 1 roethane and coating the solutlon on an aluminum shde and th p y ers 0 es ers acl'y acld with a doctor blade set at a 5 mil wet gap. The thus preme acry 16 am pared photoconductive element was uniformly electro- This formulation is coated at 3 feet per minute on a statically charged using a Xerox Model D Processor at a miIliSCuS mater and cured for 1 hour at Elecpotential of +7000 volts. After charging, the element was trometcr results Show a charge acceptance of a ut 600 vexposed to a 375 Watt GE ph R l at a di The film is used to make robot copies in the contact reof 12 inches for 2 seconds and using positive transparency flex mode. as a document to be i d, Th formed electrostatic While the invention has been shown and described with image was developed with negatively charged toner (Xerox reference to preferred embodiments thereof, it will be 914) across the photoconductive element. Again using the appreciated y H1036 Skilled in t art that Variations in Xerox ModelD Processor, the toner image was transferred f f y be made therein Without departing from the to paper by spraying positive charges on the back of the Splflt and Scope of the i npaper. After transfer of the toner image, the toner was W11at is claimed is! fused to the paper on a hot plate to yield a high quality The compounds having the mu copy of the document with high contrast, high image 0 density, and faint background. A

EXAMPLE 1v A photoconductive element was prepared by dispersing X- 2,6 bis(p-dimethylaminocinnamylideneamino)9,10 anthraquinone (the compound of Example II above) in an equal 0 Weight O P y y dissolved in Lldichloroethane and with both X moieties being the same and being selected coating the solution on an aluminum slide with a doctor fr m the group consisting of blade set at a 5 mil wet gap. The thus prepared photoconductive element was uniformly electrostatically charged using a Xerox Model D Processor at a poten- 5 6 and References Cited UNITED STATES PATENTS 3,184,482 5/1965 Steiger 260-378 5 FOREIGN PATENTS wherein R is a lower alkyl group.

2. A compound as claimed in claim 1, 2,6 bis(p-di- 979,869 1/1965 Great Bntam 260-378 methylaminobenzylideneamino)9,10 anthraquinone.

3. A compound as claimed in claim 1, 2,6 bis(p-di- LEWIS GOTTS Pnmary Exammer methylaminocinnamylideneamino)9,10 anthraquinone. 10 R. GERSTL, Assistant Examiner 

